2.2. Token Parser (Syntactic Layer)🔗

The token parser (TokenParser.lean, 790 lines) consumes the YamlToken stream and produces an Array YamlDocument. It implements the spec's grammar-layer (S) productions via hand-written recursive descent (no parser combinator library).

Key responsibilities:

• Multi-document support — handles --- and ... boundaries

• Alias resolution — substitutes *anchor references with previously anchored values

• Tag resolution — applies %TAG directive handle expansion and schema-level type resolution

• Schema application — resolves untagged scalars to typed values (null, bool, int, float, str) via the Core Schema